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Miller" , David Ahern , Dave Hansen , X86 ML , Steven Rostedt , Mathieu Desnoyers , Quentin Monnet , bpf , linux-arm-kernel , LKML , linux-riscv , linux-s390 , Network Development , linux-trace-kernel@vger.kernel.org, "open list:KERNEL SELFTEST FRAMEWORK" , linux-stm32@st-md-mailman.stormreply.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, Mar 11, 2024 at 2:35=E2=80=AFAM Menglong Dong wrote: > > By default, the kernel btf that we load during loading program will be > freed after the programs are loaded in bpf_object_load(). However, we > still need to use these btf for tracing of multi-link during attaching. > Therefore, we don't free the btfs until the bpf object is closed if any > bpf programs of the type multi-link tracing exist. > > Meanwhile, introduce the new api bpf_object__free_btf() to manually free > the btfs after attaching. > > Signed-off-by: Menglong Dong > --- > tools/lib/bpf/libbpf.c | 47 ++++++++++++++++++++++++++++++---------- > tools/lib/bpf/libbpf.h | 2 ++ > tools/lib/bpf/libbpf.map | 1 + > 3 files changed, 38 insertions(+), 12 deletions(-) > > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c > index 567ad367e7aa..fd5428494a7e 100644 > --- a/tools/lib/bpf/libbpf.c > +++ b/tools/lib/bpf/libbpf.c > @@ -8267,6 +8267,39 @@ static int bpf_object_prepare_struct_ops(struct bp= f_object *obj) > return 0; > } > > +void bpf_object__free_btfs(struct bpf_object *obj) > +{ > + int i; > + > + /* clean up module BTFs */ > + for (i =3D 0; i < obj->btf_module_cnt; i++) { > + close(obj->btf_modules[i].fd); > + btf__free(obj->btf_modules[i].btf); > + free(obj->btf_modules[i].name); > + } > + free(obj->btf_modules); > + obj->btf_modules =3D NULL; > + obj->btf_module_cnt =3D 0; > + > + /* clean up vmlinux BTF */ > + btf__free(obj->btf_vmlinux); > + obj->btf_vmlinux =3D NULL; > +} > + > +static void bpf_object_early_free_btf(struct bpf_object *obj) > +{ > + struct bpf_program *prog; > + > + bpf_object__for_each_program(prog, obj) { > + if (prog->expected_attach_type =3D=3D BPF_TRACE_FENTRY_MU= LTI || > + prog->expected_attach_type =3D=3D BPF_TRACE_FEXIT_MUL= TI || > + prog->expected_attach_type =3D=3D BPF_MODIFY_RETURN_M= ULTI) > + return; > + } > + > + bpf_object__free_btfs(obj); > +} > + > static int bpf_object_load(struct bpf_object *obj, int extra_log_level, = const char *target_btf_path) > { > int err, i; > @@ -8307,18 +8340,7 @@ static int bpf_object_load(struct bpf_object *obj,= int extra_log_level, const ch > /* clean up fd_array */ > zfree(&obj->fd_array); > > - /* clean up module BTFs */ > - for (i =3D 0; i < obj->btf_module_cnt; i++) { > - close(obj->btf_modules[i].fd); > - btf__free(obj->btf_modules[i].btf); > - free(obj->btf_modules[i].name); > - } > - free(obj->btf_modules); > - > - /* clean up vmlinux BTF */ > - btf__free(obj->btf_vmlinux); > - obj->btf_vmlinux =3D NULL; > - > + bpf_object_early_free_btf(obj); > obj->loaded =3D true; /* doesn't matter if successfully or not */ > > if (err) > @@ -8791,6 +8813,7 @@ void bpf_object__close(struct bpf_object *obj) > usdt_manager_free(obj->usdt_man); > obj->usdt_man =3D NULL; > > + bpf_object__free_btfs(obj); > bpf_gen__free(obj->gen_loader); > bpf_object__elf_finish(obj); > bpf_object_unload(obj); > diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h > index 5723cbbfcc41..c41a909ea4c1 100644 > --- a/tools/lib/bpf/libbpf.h > +++ b/tools/lib/bpf/libbpf.h > @@ -299,6 +299,8 @@ LIBBPF_API struct bpf_program * > bpf_object__find_program_by_name(const struct bpf_object *obj, > const char *name); > > +LIBBPF_API void bpf_object__free_btfs(struct bpf_object *obj); > + It shouldn't be exported. libbpf should clean it up when bpf_object is freed.